The present invention is related broadly to home appliances that employ a heat-generating apparatus and, more particularly, to home appliances that use gas burners as a controlled heat source.
Home appliances such as ranges and cooktops may use gas burners as a source of heat for cooking. Cooking appliances that may employ gas burners include freestanding ranges that include an oven and a cooktop as well as built-in cooktops. With respect to the present invention, references herein to ranges, cooktops, built-in cooktops and hobs may be used interchangablely and all may act as a platform for gas burner use. In addition, while the present application focuses on ranges and cooktops, the invention described herein may have applicability with other appliances employing heat such as laundry dryers and the like.
Gas burners utilize a gas supply such as natural gas or propane mixed with air to provide a combustible gas/air mixture which is directed to a burner head for ignition by an electrode. A user-controlled valve throttles the amount of gas available for the burner head to thereby control the amount of heat energy applied by the burner flame to a cooking vessel on the cooktop.
Air and gas is mixed and delivered to the burner head for combustion by a venturi which is generally a metal cylindrical element that has a bore extending therethrough with a constriction in the bore. Within the venturi bore, the velocity of the fluid increases as the cross section of the bore decreases, with the static pressure correspondingly decreasing. As the gas/air mixture go through the constriction, the gas/air mixture accelerates and the pressure is reduced at the constriction, causing the acceleration. Proper venturi operation results in a tight blue flame that is controllable with the throttle valve.
Generally, venturis for gas burners may be formed from brass. However, brass has been shown to have some disadvantages when employed as a material for a burner venturi. Brass becomes discolored after extended operation at elevated temperatures present in cooking operations and can be difficult to machine to desired dimensions. Further, brass can be both expensive and heavy. In their favor, brass venturis are generally dimensionally stable.
Therefore, there is a need for a burner venturi that is formed from a material other than brass that can provide at least the performance characteristics of brass.